Thanks for trying to help me.
For those not related with automotive electronics, Mercedes Benz front SAM is a control unit that gives power to several items in the front part of the car. This front SAM gives power to headlights, fog lights, and DRL lights, for instance.
In Europe, day running lights (multi-LED) work at full brightness under day light (day mode). In the evening (night mode), when low beam is activated, DRL are automatically dimmed. The dimming factor is controlled by the SAM and can be adjusted from 100% to 0% dimming in fractions of 10%. Full brighness is obtained with 14,5 VDC (with engine on, otherwise, DRL are off). For dimming function, SAM can be adjusted to get the desired brightness by decreasing the VDC going to the DRL. For instance, 80% of dimming gives a voltage of 11 VDC; 40% of dimming gives 12,8 VDC from the SAM to DRL.
Ok, my problem is I am trying to use non-original DRL lamps. These DRL LED work with a voltage 20-25% higher than the original, so they are off at 12 VDC, dimmed at 13 VDC and go to full brightness at 17,5 VDC.
The boost circuit I am asking for will work at around 13 VDC or with 17,5-18 VDC depending on the input voltage from the SAM. I can adjust the low voltage by adjusting the dimming factor in the SAM through programming with Xentry tool.
So to use these DRL LED I just need to increase the output voltage from the SAM a 20-25%. With this circuit between SAM and non-original DRL LEDs, the DRL behaviour will be the same as the original, so there will be no need to extra-wiring.
"At what frequency do you expect the input voltage to change, and with what frequency response do you expect the output to faithfully reproduce those variations?"
Once or twice a day? This is not the problem, as you can understand from this post.